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Are the Balls Juiced?

Just in the last four years, 60 more players hit 20+ home runs in 2017 vs 2014. That is more than DOUBLE the total that year (57)! No season had ever seen more than 93 players hit 20+ home runs before 2016 & 2017 both surpassed 110!

40 players hit 20 home runs for the first time in their career in 2017. 10 of them were rookies. In 2016, we saw 19 players eclipse 20 home runs for the first time and six of them were rookies. 2006 & 2008 were the only other years 5 or 6 rookies hit 20 home runs.

This video is now two years old but they noticed the rise in HRs at the All-Star Break in 2015

30+ home run hitters have nearly quadrupled since that year, with 41 players hitting at least 30 home runs in 2017 while just 11 did in 2014.

The interesting thing is that we have not seen an increase in 40+ home run hitters. We are seeing them at half the rate we did in the early to mid 2000's. From 2002-2006, the MLB averaged 9.4 hitters with 40+ home runs. Since the 2007 season - 4.3. Even if your ignore the 2014 season, when Nelson Cruz led the MLB with 40, the average only jumps to 4.6.

Actual Research

Let’s starts with some background. When a spinning baseball travels
through the air, it experiences three forces, as shown in Figure 1.
Gravity pulls the ball downward; drag slows it down; and “lift,” or the
Magnus force (assuming the ball is spinning), changes its direction. If
baseball were played in a vacuum (the “Physics 101 world”), it would
only experience gravity. Under such conditions, the initial position and
velocity (i.e., speed, launch angle, and direction) of a fly ball would
uniquely determine where it lands and how long it took to get there. - Hardball Times

In total, the changes in ball drag explain about 25 percent of the
variation in the ratio of home runs to fly balls over the last four
years.2 Wind and weather can also influence drag,
and although I controlled for those when I calculated the league-wide
numbers, I also double-checked my analysis by looking only at Tampa
Bay’s stadium, which is indoors and air conditioned. In the Rays’ home
park, I found an even stronger correlation between home run rates and
the ball’s drag coefficient.3 It doesn’t exactly come as a shock, but this is clear confirmation that air resistance influences home run rates. - FiveThirtyEight

Lately, though, the baseballs have become a lot more consistent. The standard deviation (a measure of variation) in drag coefficient between individual baseballs has dropped drastically in the last few years. - FiveThirtyEight

Although the source of that MLB-ordered report justified some
skepticism, its findings appeared to set some of the speculation about
the ball to rest. But without an equally convincing alternative, we
couldn’t declare the baseball case closed. Now, new evidence has arisen
that seems to support a contradictory conclusion: that much of the rise
in home runs can be explained by the ball. - The Ringer